Illuminance Converter

Overview

Illuminance is a measure of the amount of light that shines on a given unit of area of an object’s surface. This value depends on the human perception of the brightness of the light of different wavelengths, corresponding to different colors. Illuminance calculations are adjusted for each wavelength because humans perceive the light of a wavelength of about 550 nanometers (green) and close to it (yellow and orange) as brighter, while the light of longer or shorter wavelengths (purple, blue, red) as darker. Illuminance is often likened to how bright an object appears to the human eye.

Illuminance is inversely proportional to the area over which the light is scattered. This means that for the same light source illuminance would be greater for a smaller area, and smaller for a greater area.

The Difference Between Illuminance, Luminance, and Brightness

LuminanceIlluminance

One can think of illuminance as the light that is going towards the object, or in particular the amount of light, just as it touches the surface. This is different from luminance, which is the amount of light reflected from the surface. It is easy to remember it if you think that:

Illuminance = ILluminance = Incident Light + luminance.

Luminance = light Leaving the surface. Leaving light

Our perception of brightness can be either the perception of the light reflected from the surface (luminance), or light going to the surface (illuminance), or even the total amount of light in the room. It could also be a combination of some or all of these, depending on the situation. We could also think of the area as being bright, or the object as being bright, or the light source as being bright. This is one of the reasons why the word "brightness" is not widely used in science.

Units

One of the most common units for measuring Illuminance is a lux. It is an SI unit. One lux is one lumen per square meter. A foot-candle is a non-metric unit for measuring illuminance. It is used in photography and film, as well as in some other areas. The word “foot” is used to refer not to body parts but to distance: a foot-candle is the illuminance of a one-candela light source per square foot, measured from one foot away.

Light Meter

A light meter is a device that measures illuminance by converting the light detected by the photodetector to electricity and then measuring it. There are light meters calibrated in different units, but lux meters are some of the most common ones. Light meters are widely used in photography and videography, in the area of occupational safety, in museum conservation, in plant cultivation, and in many other areas of human activity, where light plays an important role.

Illuminance in Work Safety

People who work in dim lighting conditions may suffer from deterioration of vision, depression, and other physiological and psychological problems. Therefore many health and safety codes for workplaces include specifications on what the minimum illuminance should be in the work environment. This is generally measured by the light meter. The meter adjusts the reading based on the area of the room to ensure that there is enough light for the entire room.

Illuminance in Photography and Videography

Cameras are equipped with devices for measuring illuminance, because a camera has to allow an adequate amount of light onto the film or the imaging sensor, based on the illuminance of the object being photographed. The illuminance in lux is then converted to determine the exposure necessary, taking into consideration the specifications of the camera and the photographer’s or videographer’s needs. Photographers and videographers also measure the illuminance to ensure that the light setup in the studio or on location is adequate. This can be done either by the camera or by an external light meter.

Still cameras can take pictures in low light conditions by opening the shutter for a long time, to allow enough light in. Video cameras are limited in this respect and need artificial lighting in dark conditions, otherwise, the resulting video will not be bright enough. Some cameras work better in low light than others — camera manufacturers sell cameras designed for these conditions.

Low Light Cameras

Cell phone camera and lens

Low-light cameras can either have superior optics or superior electronics. The optics allow more light in and then work with the extra light. Electronics have less light but do a good job processing the light that is available. The superior electronics often produce more of the shortcomings described below compared to the cameras with superior optics. The drawbacks of powerful optics are that the camera lenses are large, heavy, and much more expensive.

Compact camera type 1/1.7” (7.60 x 5.70 mm) CCD sensor and lens

In addition, a camera will have either one chip to process the light that is coming in, or three — one for each color (red, green, and blue). The latter type of camcorders is better because they scatter less light when breaking it down into three components by using a prism, compared to a filter used by the one-chip camera.

There are two different types of image sensors available — charge-coupled device (CCD) chips and complementary metal-oxide-semiconductor (CMOS) chips. In CCD chips а sensor for capturing light can sometimes be combined with аn image processor. CMOS chips can also combine the two together, although only in inexpensive cameras. In professional ones, the sensor and the image processor are usually separate. CCD chips generally produce the better quality video but CMOS chips are cheaper and less power-hungry.

The size of the chip also affects the quality of photographs and video — the bigger it is, the higher the quality of the image, and the smaller it is — the more noise it produces in low-light conditions. Larger sensors also require more powerful and heavy optics. They are used in more expensive cameras. It allows one to shoot professional-quality video even with a still DSLR or mirrorless camera, such as a Canon 5D Mark II or Mark III, where the sensor is 24 x 36 mm in size.

The standard for how the light qualities of the camera are determined is not universal; it depends on the manufacturer. An attempt to create a universal standard was made by the Electronic Industries Alliance, but currently, it is not universally accepted. This means that one camera that records in 2 lux may produce a very different quality of video from another camera with the same lux specifications.

Cameras that are marketed to work in low light conditions may not provide adequate quality, with problems including out-of-focus video and noise, such as grain and after-images for the bright areas. To address some of these issues the videographer can do the following:

If there is not enough light and the object is static, it is better to mount the camera on a tripod

• Mount the camera on a tripod;
• Use the manual mode;
• Avoid zooming in;
• Disable automatic gain (ISO) selection and autofocus;
• Set shutter speed to 1/30;
• Diffuse the lights;
• Use all the lighting already available in the environment, such as street lights and moonlight.

Despite the lack of standardization of information in lux sensitivity for different camcorders, it is still a good idea to get one with lux of 2 or less. It is important to note that even if the camera produces good quality video at low light, its lux value is the light that is coming towards the subject, but the camera actually catches the light that is reflected from it. The amount of light depends on the subject (some colors reflect light better than others) and on the location of the light. If the light is too far from the subject to illuminate it well, or if the subject is too far from the camera, then the quality would be diminished.